HE HAS been described as one of the greatest “unknown” Scottish poets.

Now the words of Charles Hamilton Sorley, the war poet whose work inspired Robert Graves and Siegfried Sassoon, are to be set to music by the leading composer Sir James MacMillan.

The war poems of Sorley, an Aberdonian killed by a sniper in the Battle of Loos in 1915 at the age of 20, so impressed Graves that he gave his work to fellow poet Sassoon, and it is believed Sassoon passed on his poetry to Wilfred Owen when the two met in Edinburgh in 1917.

The poems are some of the earliest to be published that expressed scepticism about the war and the horrors that it produced for those who fought in it.

He was described by Graves as one of three poets – along with Owen and Isaac Rosenberg – “of importance” to have been killed in the war.

A collection of Sorley’s poetry was published posthumously as Marlborough and other Poems (1916) and went through six editions in its first year.

As part of the 14-18 NOW cultural events marking the war’s centenary, Sir James will set his words to music and work with tenor Ian Bostridge.

The world premiere of the work, an oratorio entitled All the Hills and Vales Along, will be a centrepiece of the fifth Cumnock Tryst festival in October later this year, before being performed at the Barbican in London.

Sorley was the subject of an acclaimed play, It Is Easy to Be Dead, by Neil McPherson in 2016.

Mr McPherson said: “Sorley is arguably Scotland’s greatest writer who no one has heard of. He isn’t very well known, but he was among the first poets to express scepticism and disillusionment with the war.

“In a way he was the first of the War Poets, he ‘got it’ and got it published first – and how good his poems are at the age of 20, who knows how great a writer he could have been.”

Sir James’ piece will be performed by the Edinburgh String Quartet, the Cumnock Tryst Festival Chorus and the Dalmellington Band.

The composer said: “Years ago I was given a book of Poems of the First World War and I immediately turned to the ones by Owen, Sassoon and Graves.

“However, I was also directed towards a beautiful poem All the Hills and Vales Along by CH Sorley and I made a mental note of this at the time. I returned to it years later, along with others by him in the book, which are now set in the oratorio.”

The oratorio features settings of five of Sorley’s poems including When You See Millions of the Mouthless Dead, a work that was discovered in his kit bag after his death.

Sir James said: “I have worked with Ian over many years including writing the solo part in my Gloria for him.

“I have been keen to invite him to the Cumnock Tryst since its inception and am delighted that he will be joining us at our fifth festival as the soloist in All the Hills and Vales Along.”

The full programme for the fifth Cumnock Tryst Festival will be announced later in the spring.